Piezo-electric-crystal apparatus



A. cRossLEY mmmm/ IN VEN TOR A T T0 RNE Y ed Crass March 8, 1927.

PIEZO ELECTRIC CRYSTAL APPARATUS Filed Feb. 26. 19@

. 25 .tal for V avoidin Patented Mar. 8, 19,27. l

UNITED STATES 1 y y '1,619,854 ,PATENT OFFICE'.

ALEEED onossLEY, OE WASHINGTON, lDIsTIIIcT or COLUMBIA, AssIeNOEro AWIaED K RADIO, ING., or NEW YORK, N. Y., A CORPORATION or DELAWARE,

P IEzO-ELEcTEIc-CBYSTAL APPARATUS.

Application led February 26, 1926.` Serial No. 90,931. 4

My invention relates broadly to piezoelectric crystal apparatus and more particularly to a method of securing the piezo-electric crystal within a container during the 5 rapid mechanical vibration .thereof-in the process of sustaining oscillations in an electrical circuit. i

One of the objects of my invention is to provide a construction of securing device for piezo-electric crystals enabling the free mechanical vibration ofthe crystal in spaced relation to a crystal holding device. y Another object bf my invention is to vprovide a retaining ring for piezo-electric c stals for centering a c stal within .a suita le housing at the same tune that the crystal is free to vibrate mechanically in the sustaining of electrical oscillations in an electron tube system. v l

Still another object of my invention is to rovide a construction of retaining device or piezo-electric crystals in which a mini- I num area of contact is existent between the lretaining device and the piezo-electric crysall obstructions to the mechanical vibration of the crystal during the process of electrical oscillation generation in an electron tube circuit associated with the piezo-electric crystal.

My invention will be more' fully understood from the specicationhereinafter following by referencefto the accompanying drawings, in which:

Figure l is a cross-sectional view taken through a piezo-electric crystal holder show` ing a retaining ring in accordance with my vinvention in position for centering a iezoelectric crystal within the housing; lig. 2 is a plan view of the retaining device for piezo-electric crystals taken on a sectional line 2-2 through the piezo-electric crystal holder; Fig.' 3 is a cross-sectional view through the iezo-electrio c stal housing and the retaimng ring for gui ing the piezoelectric crystal within the houslng on line 3f-3 of Flg. l; Fig. 4'is a plan view of a modified form of retaining rin for piezoelectric crystals; and Fig. 5 is a cross-sectional view taken on line 5-5 of Fig. 4 showing the vmodified form of retaining ring in osition within the piezoelectric crystal ousing for4 guidlng a piezoelectric crystal therein. Y.

My invention contemplates the positloning of a piezo-electric crystal within a crys- :centrally therethroughA secured interiorly .thereof at 4 for the supportv of a spring agmentary tal housing similar to the lconstruction illustrated in my Letters Patent No. 1,572, 773, issued February 9, 1926, with special means for retaining the piezo-electric crys'- tal ycentrally with-ln the housing 4and yet eo 'without' obstruction to the free mechanical Vibration9 thereof. I providel a retaining ring. member which has a 'central aperture therein of a slze sullicient to admit the piezoelectric crystal .and having inner dimensions defined by substantially point contact portions Vv which `form guide members for the 'piezo-electric crystal. The guide rin is substantially' less than the thickness of t e crystal so that thereis no tendency for the guide I'ing to interferei in any manner whateverv with the free mechanical vibration of the plezo-electrie element. Tlre guide ring is 4suitably secured to the interior lof a suitable housing and spaces the c stal away from l the Wall ofthe housing vlvvliile it is free to i mechanically vibrate in the sustaining of electrical oscillations in an associated electron tube circuit. Referrin to the drawings in more detail, referenceA c aracter l designates a housing for a piezo-electrical crystal Ihaving a top closure 2 and abottomclosure 11,. The closure 2 has a terminal post 3 projecting guide member 5. rlhe guide member 5 has a vertically extending guide post 6' centered in its lower extremity, the post connecting through resilient connection 7 with the guide 5. The post 6 is secured to :a late 8, which normally rests upon the sur ace of piezo-electric crystal 9 within the housing. The piezo-electric crystal 9 is centrally positioned within the housing by means of the retaining ring 10 of my invention. The retaining ring`10 i`s provided as re resented in Fig. 2 with a number of space contacting portions, 20 separated by substantially semicircular cutaway portions 21. In` this way, only an extremely small area of the materialY of the retaining ring 10 is actually adjacent the sidesof the'piezo-electric crystal '9. I may further reduce the rubbing contact between the retaining ring 10 and the sides of 105 vthe piezo-electric ycrystal by yconstructing the retaining ring as represented in Fig. 4 v where the inner periphery of the retaining ring is defined by a plurality of Aabrupt points 22 separated by triangular cutaway 110 ring can be thereo sections 23. In this manner the triggering action is considerably improved. That is to say, load on the crystal 1s substantially removed and loading normally tends to render the crystal-sluggish in starting oscillation. The action of starting oscillations quickly may be termed the triggering effect and it is for thepur ose of reducing fr ictionbetween the wal s of the guide device and the sides of the piezo-electric crystal that I have designed the retaining iring 10. Bottom plate 11 which closes the housing 1 may fit into side guide portions 16 and 17 secured to the plate 14 which forms a part of the frame 15. The upper terminal 3 may be contacted' with a sprin clip 18 secured to the frame 15 for establishing connection with the piezo-electric crystal as desciibed in my patent before mentioned. The retaining ring 10 is constructed of suitable insulation material such as bakelite cut away in the manner heretofore described. The cutting away of the bakeliteI guide ring reduces the friction between the crystal and the retaining rin considerably; 'The retaining (gitted into the ttom of the crystal container by employing a pressed fitwith the side walls of the container or it maybe secured to the bottom plate by screws 12 as I have illustrated in the drawings. The binding screws 12 are employed to secure both the bottom conductive plate 1l and the insulated retaining ring 10 in position with respect to the housingl. While I have described the piezo-electric crystal housing as employing a bakelite retaining member 10, it will be understood that the member 10 ma be constructed of any suitable material -an thatvvarious shapes may b e imparted to this guide ring and that no limitations upon my invention are vintended other than those imposed by the scope of the appended claims. v

What I claim and desire to secure by Letters Patent of the United States is as follows: i

1. A piezo-electric crystal apparatus comprisin in combination with a piezo-electric crysta a housing for said crystal, and means for locating said. crystal substantially in the center of said housing, comprising a retaining ring having a plurality of inwardly directed contacting portions arranged to substantially embrace the sides of said crystal, while permitting free mechanical movement 2. Piezo-electric crystal apparatus, comprising in combinationI a housing, a piezoelectric crystal, a retaining ring forcentering said piezo-electric crystal in said housin said retaiiiin ring comprising a, plur it portions arran ed to embrace the periphery of said piezoectric crystal for preventin substantial horizontal movement thereo while ermitting free mechanical vibration of sai crystal in a direction transverse to the plane of said retaining ring.

3. Piezo-electric crystal apparatus comprisingV in combination a lhousing electric crystal secured Within said housing, a retaining ring for centering said crystal within said housing, said retaining ring having a thickness substantially less than l the thickness of said piezo-electric crystal and having inwardly directed faces for embracing the sides of said piezo-electric crystal for preventing substantial movement of said piezo-electric crystal in a direction parallel to the plane of said retaining ring while ermitting free transverse movement of sai piezo-electric crystal in accordance with its natural frequency characteristics.

4. Piezo-electric crystal apparatus comof diametrically opposed` contacting a piezo- .y

prising in combination a housing, a piezo-.

electric crystal, and means :for mounting said piezo-electric crystal within -said housing and substantially removed from the walls thereof comprisin a retaining member having a' plurality o?? faces substantially surrounding the sides of saidpiezo-electric crystal While said crystal isfree to vibrate mechanically Within said housing.

5. Piezo-electric crystal apparatus comprising in combination a pair of conductive plates, a piezo-electric crystal supported bctween said plates, a retaining ring member oi insulating material mounted on one of said lates and extending 'to a distance substantially less than the thickness of said crystal and substantially-spaced away from the other or' said plates, said ring member having inwardly directed faces arranged to embrace the sides of said piezo-electric crystal for preventing*` substantial movement vthereof in planes parallel to the plane of the 4retaining ring, While permitting free mechanical vibration of the piezo-electric crystal at the natural frequency thereof.

In testimonyV whereof I aiix my signature.

ALFRED cRossLEY.

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